Field of the Invention
The present invention relates to an organic light emitting diode (OLED) display device, and more particularly to a data processing method and apparatus for an OLED display device, which are capable of adaptively controlling a peak luminance in accordance with compensation for degradation, thereby securing a sufficient compensation margin.
Discussion of the Related Art
An organic light emitting diode (OLED) display device is a self-luminous device in which an organic light emitting layer emits light through re-combination of electrons and holes. Since the OLED display device exhibits high luminance, and uses a low drive voltage while having an ultra-slim structure, the OLED display device is expected to be a next-generation display device.
Such an OLED display device includes a plurality of pixels, each of which includes an OLED constituted by an anode, a cathode, and an organic light emitting layer interposed between the anode and the cathode, and a pixel circuit for independently driving the OLED. The pixel circuit includes at least a switching transistor, a storage capacitor, and a drive transistor. The switching transistor charges the storage capacitor with a voltage corresponding to a data signal in response to a scan pulse. The drive transistor controls the amount of current supplied to the OLED in accordance with the level of the voltage charged in the storage capacitor, to adjust the amount of light emitted from the OLED. The amount of light emitted from the OLED is proportional to the amount of current supplied from the drive transistor to the OLED.
In order to reduce consumption of electric power, related art OLED display devices use a method for controlling current supplied to a display panel by controlling a peak luminance (maximum white luminance) in accordance with an input image. As shown in FIG. 1, such a related art OLED display device controls a peak luminance, using a peak luminance control (PLC) gain determined in accordance with an average picture level (APL) of each frame. For example, the related art OLED display device achieves reduction of power consumption by decreasing the peak luminance to 100 nit, using a PLC gain of 1, when APL is as high as 100%, and increasing the peak luminance to 500 nit, using a PLC gain of 4, when APL is as low as 25%.
OLED display devices have a problem in that OLEDs are non-linearly degraded with passage of time due to electrical stress, thereby exhibiting a luminance deviation for the same data and, as such, a latent image is generated.
In order to solve this problem, OLED display devices use a degradation compensation method for achieving an increase in luminance by estimating a degree of degradation, based on accumulated data, and compensating data, based on the estimated degradation degree, as shown in FIG. 2.
However, such a related art degradation compensation method has a problem in that, although degradation compensation is possible in low and middle grayscale regions provided with a sufficient compensation margin, such degradation compensation is impossible in high grayscale regions provided with an insufficient compensation margin.
Meanwhile, when a maximum gamma voltage is first increased to secure a desired compensation margin, there are problems in that consumption of electric power is increased, and grayscale rendering capability is degraded, thereby causing degradation of picture quality.